The most common problem in smoke detectors is faulty batteries, which cause the detector to beep until a new batter is installed. In generally, experts recommend replacing faulty smoke detectors instead of attempting to repair them.
Almost all areas require smoke detectors to be placed throughout homes, and units are often required in bedrooms and above staircases. While older smoke detectors were powered solely by batteries, newer regulations often mandate that units be hardwired to the power in addition to having a battery backup. As a result, troubleshooting a unit that constantly beeps might entail checking its wiring, which can be dangerous for the untrained.
Smoke detectors have a "test" button used to ensure proper operation, and units should be checked approximately every six months. While it might be tempting to open up a faulty unit, doing so is potentially dangerous. Most smoke detectors use a small amount of americium, which emits ionizing radiation. While the amount used it small, it can produce symptoms if even a small amount is ingested.
Another reason to replace broken smoke detectors is to avoid relying on a faulty unit. If part of a smoke detector is accidentally broken while attempting repairs, it can cause the unit to fail to operate when needed. Paying a bit more to ensure proper operation is a wise investment.